Just because your email account doesn't offer IMAP access doesn't mean you have to put up with reading and deleting the same messages ad nauseum. Web how-to site Webmonkey offers a detailed rundown on setting up the free Dovecot server on your system to pull in any kind of mail and dish it out in that synced, folder-sorted, always-accessible IMAP way. This guide is specific to Ubuntu and Debian-based systems, but Dovecot is available for lots of open-source platforms. If running your own box seems like a bit of overkill, you can always set up Gmail with IMAP as a go-between.